We have produced new and compelling evidence that the Universe is smoothly filled with a mysterious anti-gravity material known as "dark energy". In particular, our data shows dark energy acting in two separate ways. Firstly, we have observed how dark energy opposes gravity by speeding up the overall rate of expansion of the Universe. Secondly, we have observed how dark energy opposes gravity by slowing down the growth of clusters and superclusters with time. We have accurately observed both of these effects over the last 7 billion years, which is the most distant measurement yet achieved. Our results have been produced by a careful analysis of the largest existing map of the distant Universe, measuring the positions of about 200,000 galaxies, which has taken us 4 years to assemble and was completed this year.